Electrochemical devices are attracting much focus within a large area of applications. Envisaged application areas include security devices, food quality indicators, parking tickets, timers for medical compliance packaging, etc. One particular area that is currently attracting much focus is the prospect of providing low cost, easily applied electronic circuits on plastic and paper-based packages of various kinds. For example, such circuits are envisioned for providing information such as age, handling history, current status etc. of the content of such a package.
In order to provide for such functionality, circuits typically need to include conventional electronic components such as transistors, resistors, capacitors, display cells etc. These components all need to be cheap, environmentally friendly, and preferably possible to manufacture using conventional manufacturing processes such as printing equipment.
Using such components, logical and analogue circuits can be designed as described, for example, in US-20040211989. One component that is desirable for a large number of applications is a timer that opens or closes a circuit at a predetermined point in time. Such a timer switch can indeed be provided using conventional arrangements in line with the teachings of US-20040211989, for example using ring oscillators in combination with other logic. However, such arrangements require complex circuit design and typically suffer from slow switch characteristics (i.e. switching from open to closed or from closed to open occurs gradually during an extended period of time). Hence, such arrangements are undesirably complicated and unreliable and there is thus a need for a low-cost and reliable timer switch that is suitable for use in combination with electrochemical components based on conducting organic materials.